TRANS-CHELATING CHIRAL PERALKYLDIPHOSPHINE LIGANDS -BIS[1-(DIALKYLPHOSPHINO)ETHYL]-1,1''-BIFERROCENES (ALKYLTRAPS) AND THEIR TRANSITION-METAL COMPLEXES

New chiral peralkyldiphosphines (S,S)-2,2 ''-bis[(R)-1-(dialkylphosphi no)ethyl]-1,1 ''-biferrocenes ((R,R)-(S,S)-alkylTRAPs) were synthesize d from (R)-N,N-dimethyl-1-ferrocenylethylamine in four steps in 38-68% overall yields (MeTRAP: 38%, EtTRAP: 68%, PrTRAP: 53%, BuTRAP: 56%, i -BuTRAP: 51%, i-PrTRAP: 42%). The reactions of alkylTRAP (Et-, Bu-, i- Bu, and i-PrTRAP) with 1 molar amount of PdBr2 gave trans-[PdBr2(alkyl TRAP)] in good yields. The X-ray crystal structures of these palladium complexes revealed that alkylTRAPs coordinated to a palladium atom in a trans-chelating manner regardless of the P-alkyl substituents. The structures of palladium complexes of Et-, Bu-, and i-PrTRAP had nearly Ct-symmetry, but that of i-BuTRAP was deviated from Ct-symmetry signi ficantly. AlkylTRAPs also reacted with [PtCl2(MeCN)(2)] and [RhCl(CO)( 2)](2), giving the corresponding trans-chelate platinum and rhodium co mplexes. The crystal structure of trans-[RhCl(CO)(BuTRAP)] revealed th at the conformation of the BuTRAP ligand in the complex was almost the same as that in the palladium complex trans-[PdBr2(BuTRAP)].